In the course of more than 100 years of Friedel-Crafts chemistry, two catalysts achieved preeminence. Anhydrous aluminum trichloride was introduced by Friedel and Crafts themselves and maintained its wide use despite some of its unfavorable properties, i.e. it is a subliming solid with only limited solubility in apolar or hydrocarbon solvents. Boron trifluoride became a significant catalyst since the 1930's based on fundamental studies by Meerwein and others. As it is a low boiling gas (bp. -100.degree. C.), some of its more convenient complexes are frequently used, albeit reduced in reactivity, such as the ether complex. Although a significant number of other Lewis acid halide (and pseudo halide) catalysts are also applied on occasion, none of them achleved similar wide applicatlon. Slnce the 1960's, superacidic catalysts based on antimony pentafluoride gained significance. Friedel-Crafts catalysts are well reviewed (see G. A. Olah, "Friedel-Crafts Chemistry", Wiley Interscience, New York, 1973; G. A. Olah, G. K. S. Prakash and J. Sommer, "Superacids", Wiley-Interscience, New York, 1986).
All the active Friedel-Crafts catalysts, such as the reactive halides of boron, aluminum, and gallium, are substantially volatile or sublime and consequently can not be used as solid or supported catalysts in heterogenous gas phase processes. This is a serious shortcoming of Friedel-Crafts chemistry forcing it to be usually operated in closed, batchwise reactors. In contrast, the plurality of modern chemical and petrochemical processes increasingly use heterogenous catalytic gas phase technology. My invention now discloses a new class of highly efficient Friedel-Crafts catalysts which can also overcome this limitation.